Mixed-metal uranium(VI) iodates: Hydrothermal syntheses, structures, and reactivity of Rb[UO2(CrO4)(IO3)(H2O)], A(2)[UO2(CrO4)(IO3)(2)] (A = K, Rb, Cs), and K-2[UO2(MoO4)(IO3)(2)]

摘要

The reactions of the molecular transition metal iodates A[CrO3(IO3)] (A = K, Rb, Cs) with UO3 under mild hydrothermal conditions provide access to four new, one-dimensional, uranyl chromatoiodates, Rb[UO2(CrO4)(IO3)(H2O)] (1) and A(2)[UO2(CrO4)(IO3)(2)] (A = K (2), Rb (3), Cs (4)). Under basic conditions, MoO3, UO3, and KIO4 can be reacted to form K-2[UO2(MoO4)(IO3)(2)] (5), which is isostructural with 2 and 3. The structure of 1 consists of one-dimensional (1)(infinity)[UO2(CrO4)(IO3)(H2O)](-) ribbons that contain uranyl moieties bound by bridging chromate and iodate anions as well as a terminal water molecule to create [UO7] pentagonal bipyramidal environments around the U(VI) centers. These ribbons are separated from one another by Rb+ cations. When the iodate content is increased in the hydrothermal reactions, the terminal water molecule is replaced by a monodentate iodate anion to yield 2-4. These ribbons can be further modified by replacing tetrahedral chromate anions with MoO42- anions to yield isostructural, one-dimensional (1)(infinity)[UO2(MoO4)(IO3)(2)](2-) ribbons. Crystallographic data: 1, triclinic, space group P (1) over bar, a = 7.3133(5) Angstrom, b = 8.0561(6) Angstrom, c = 8.4870(6) Angstrom, alpha = 88.740(1)degrees, beta = 87.075(1)degrees, gamma = 71.672(1)degrees, Z = 2; 2, monoclinic, space group P2(1)/c, a = 11.1337(5) Angstrom, b = 7.2884(4) Angstrom, c = 15.5661(7) Angstrom, beta = 107.977(1)degrees, Z = 4; 3, monoclinic, space group P2(1)/c, a = 11.3463(6) Angstrom, b = 7.3263(4) Angstrom, c = 15.9332(8) Angstrom, beta = 108.173(1)degrees, Z = 4; 4, monoclinic, space group P2(1), a = 7.3929(5) Angstrom, b = 8.1346(6) Angstrom, c = 22.126(2) Angstrom, beta = 90.647(1)degrees, Z = 4; 5, monoclinic, space group P2(1)/c, a = 11.3717(6) Angstrom, b = 7.2903(4) Angstrom, c = 15.7122(8) Angstrom, beta = 108.167(1)degrees, Z = 4. [References: 50]